Field of the Invention
The present invention relates to a liquid discharge apparatus and a liquid discharge head.
Description of the Related Art
A liquid discharge apparatus configured to conduct recording by discharging, from a liquid discharge head for discharging liquid such as ink, a liquid onto a recording object is required to conduct a more accurate recording at high speed. A liquid discharge head includes a mechanism configured to discharge liquid (hereinafter referred to as discharge mechanism portion) including a pressure chamber, a discharge port communicating with the pressure chamber, a pressure generating unit that is provided for the pressure chamber and is configured to generate a pressure for discharging liquid through a discharge port, and a flow path connected to the pressure chamber. In order to meet the requirement described above, it has been proposed to two-dimensionally arrange a large number of the discharge mechanism portions in a substrate of the liquid discharge head.
In Japanese Patent Application Laid-Open No. 2012-045889, there is disclosed a liquid discharge head including a plurality of discharge mechanism portions that are two-dimensionally arranged and a plurality of supply paths (liquid introducing chambers) connected to a common liquid chamber (manifold) for storing liquid. In the liquid discharge head disclosed in Japanese Patent Application Laid-Open No. 2012-045889, pressure chambers of the large number of discharge mechanism portions are connected to each of the plurality of supply paths.
Further, in Japanese Patent Application Laid-Open No. 2006-123397, there is disclosed a liquid discharge head including a plurality of discharge mechanism portions that are two-dimensionally arranged and a plurality of common liquid chambers (auxiliary manifolds), in which pressure chambers of the plurality of discharge mechanism portions are connected to each of the common liquid chambers via flow paths. In the liquid discharge head disclosed in Japanese Patent Application Laid-Open No. 2006-123397, a plurality of pressure chamber arrays each including a plurality of pressure chambers are assigned to one common liquid chamber, and the pressure chambers that belong to the plurality of pressure chamber arrays are connected to the one common liquid chamber. Pressure generating units (actuators) of pressure chambers that belong to pressure chamber arrays adjacent to each other among the plurality of pressure chamber arrays assigned to the one common liquid chamber are driven at different timings.
In a liquid discharge head in which a large number of discharge mechanism portions are arranged at high density, there is a problem in that the discharge mechanism portions (pressure generating units) interfere with each other due to a pressure fluctuation occurring when the discharge mechanism portions are driven, and thus, a discharge state of liquid of the discharge mechanism portions fluctuates to lower quality of the recording. Further, when discharge mechanism portions of a large number of pressure chambers are electrically driven at the same time, there is a problem in that a peak value of drive power becomes larger, and thus, the discharge state of the discharge mechanism portions fluctuates due to a voltage drop or the like to lower the quality of the record.
In the liquid discharge head disclosed in Japanese Patent Application Laid-Open No. 2012-045889, in order to prevent a pressure wave generated in one pressure chamber from directly propagating to another pressure chamber, the pressure chambers are arranged so that openings of flow reducing portions connecting a pressure chamber and a supply path are not opposed to each other. However, interference among the discharge mechanism portions also occurs due to other factors than propagation of a pressure wave.
Specifically, at a time when a pressure chamber is pressurized by a pressure generating unit to discharge liquid, the liquid flows back through a flow reducing portion and flows into a supply path to increase the pressure in the supply path. The extent of the pressure increase in the supply path depends on the number of discharge mechanism portions that are driven at the same time. Therefore, not only does the discharge state of the discharge mechanism portions that are driven at the same time fluctuate, but also menisci of discharge mechanism portions that are not driven fluctuate to affect the subsequent discharge. Further, immediately after liquid is discharged, the liquid is supplied toward a discharge mechanism portion that has discharged the liquid, and thus, the liquid flows in the supply path to reduce the pressure. Such pressure fluctuations due to liquid flow and resulting fluctuations of the discharge state of the discharge mechanism portions cannot be prevented through alleviation of direct propagation of a pressure wave.
In the liquid discharge head disclosed in Japanese Patent Application Laid-Open No. 2006-123397, a large number of pressure chambers connected to one common liquid chamber are grouped into four pressure chamber arrays, and pressure generating units of pressure chambers that belong to one pressure chamber array are driven at a timing different from that of pressure generating units of pressure chambers that belong to another adjacent pressure chamber array. The pressure generating units of the large number of pressure chambers are grouped into four groups when driven, and thus, the peak value of drive power is lowered, and pressure fluctuations accompanying the drive can be alleviated. However, pressure generating units of a plurality of pressure chambers that are connected to the same common liquid chamber and that belong to the same pressure chamber array are driven at the same time, and thus, occurrence of the interference cannot be avoided.
Further, in order to connect a plurality of pressure chambers that belong to one pressure chamber array to one common liquid chamber, as illustrated in FIGS. 3A to 3C of Japanese Patent Application Laid-Open No. 2006-123397, the common liquid chamber is required to be provided between the pressure chambers and the discharge ports in the height direction. The reason is that, if a long common liquid chamber to which the plurality of pressure chambers can be connected is provided on a side opposite to the discharge ports, a support substrate for maintaining an entire shape is divided and a necessary strength cannot be maintained. If the common liquid chamber is provided between the pressure chambers and the discharge ports, it is inevitable that the common liquid chamber is elongated in a horizontal direction and is in a narrow shape. When a large number of pressure chambers are connected to the narrow common liquid chamber and pressure generating units of the large number of pressure chambers are driven, occurrence of the interference due to liquid flow cannot be avoided, and the discharge state fluctuates.